The present invention relates to an apparatus and a method for controlling the steering of an industrial vehicle and, more specifically, to an apparatus and a method for controlling the steering of a forklift truck with high precision.
Japanese Patent Application Publication 2000-344122 discloses a control apparatus and a method for controlling in a full electric manner the steering of an industrial vehicle such as a forklift truck through compensation for the detection errors of wheel angle of steerable wheels. When a turn-on of a start switch of the forklift truck is detected, the steerable wheel is turned automatically by a wheel angle changing means to either one of its steering limit positions and the turned angle of the wheel is detected by an angle detecting means, and then the steerable wheel is turned to the other steering limit position by the angle detecting means and the turned angle of the wheel is detected by the angle detecting means. The above-described steering control apparatus modifies the value of the wheel angle which is used as the reference in changing the wheel angle by the wheel angle changing means, based on the wheel angles of the steerable wheel at its steering limit positions.
In the above-described steering control apparatus, however, the industrial vehicle cannot be used for its intended purpose during the detection of the wheel angle at the steering limit positions. In the case of a steering control apparatus in which the steering wheel and the steerable wheel are mechanically linked, the steering wheel is turned automatically without the manipulation by the operator, which may give the forklift operator an odd feeling. In addition, the detection of the wheel angle at the steering limit position is performed by the stationary steering, so that not only the wear of the tire is accelerated, but a force greater than the restoring force of the tire needs to be applied in the detection of the wheel angle at the steering limit position.
The present invention, which has been made in light of the problems mentioned above, is directed to providing an apparatus and a method for controlling the steering of an industrial vehicle that detects accurately the wheel angle at steering limit position without performing the stationary steering and is applicable to a mechanically linked steering control mechanism, as well as to a steer-by-wire steering control mechanism.